The invention relates to a rotary casting apparatus and method. More particularly, it relates to an apparatus and method wherein the quality of castings and the reliability of production of quality castings is enhanced with the aid of centrifugal force and a vacuum.
Conventional investment casting of the type used to produce cast parts which may be furnished for use as, for example, rings in the jewelry industry begins with the production of a master .-+.tree" having a thin central cylindrical core and branches extending therefrom at an acute angle with respect to the core. The branches end in members having the shape of the objects to be cast. A flexible resilient mold is generally cast about the master and then the master is removed by stretching the mold and, if necessary, selectively parting the mold. The mold is carefully reassembled, and a molten material, such as wax, is poured into the mold. The mold is then cut away, leaving a wax duplicate of the master.
A casting cement mold is then created with the wax duplicate disposed therein and the core extending to a surface of the mold. The mold is heated to melt the wax, which is allowed to flow from the mold. Liquid metal is then poured into the opening corresponding to the core.
This method has several shortcomings. The liquid metal tends to be rapidly cooled and in many instances enough metal does not run down through the branches and into the members being cast to completely fill the members. Further, gases evolved during the casting process do not escape rapidly enough to prevent at least some of the castings from being adversely affected. In either case, castings are produced that are not usable and the material from which these castings are formed must be recast. This results in a loss of labor and materials which greatly increases the cost and limits the productivity of the casting process.
It is a principal object of the invention to provide an apparatus and method for casting which consistently produces castings of high quality.
It is an object of the invention to provide a casting apparatus which is relatively simple and inexpensive.
It is a further object of the invention to provide a method of casting which is relatively inexpensive to use.
It is yet another object of the invention to provide an apparatus and method of casting which efficiently fills the mold with molten material.
It is still another object of the invention to provide an apparatus and method of casting which efficiently removes evolved gas from the mold.